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Old 03-30-2011, 12:56 AM
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Question A4 1.8T cold start problem - low rpm

When my A4 B5 1.8T sits for 10 hours or longer, it needs quite a few cranks (10 seconds or so) until it starts. Even then, it starts slowly and rough.

When it was working fine, rpms would go higher in the first minute after a cold start, bu it no longer does that. Almost like a missing "choke" - or whatever the equivalent is for these engines.

Do you know what controls the rpm increase for a cold engine? What could cause them to stay low like it would be for a warm engine?

I already cleaned the MAF, replaced fuel filter + spark plugs. Temp display is fine otherwise, but I'll try replacing the sensor next.
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Old 03-30-2011, 10:09 AM
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On the first start of the day mine idles low as well. Any other cold start (but not the first start in a long period of time such as an overnight) it will idle high, as it should, for about a minute.

No clue what this is all about either...
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Old 04-03-2011, 01:08 AM
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Swapping out the coolant temp sensor fixed my cold start problem.

I didn't think it would since the temp gauge showed correct values, but maybe it's driven by another sensor.
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Old 04-03-2011, 02:58 PM
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Does the idle surge?
What is a "high" idle for you?

Cold start mine will be about 850 all day long. Warm start again,850. My coolant temp gauge is shot and no starting problems.

I would definitely check the sensor governing the intake air temp and maybe check 02's? Could be something simple, could be...lol

Another thing to check are vacuum lines!!!
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Old 04-03-2011, 10:42 PM
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shot in the dark but

Starter solenoid? Starter Motor? Loose wiring in the starting circuit?

Like wise, mine starts in 2-3 seconds and idles at 850 hot/cold
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Old 04-04-2011, 12:48 AM
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Replace the hall sender / crank position sensor. Usually when these sensors are cold, they have less electrical resistance, while warm they may function well but not when cold.
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Old 04-04-2011, 01:23 AM
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See if your suction pump is disconnected. Happened to me and caused starting problems.
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Old 04-04-2011, 01:32 AM
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The rpm's are fine. It's just that if the engine is cold, you can floor it and get only a turtle crawl. Once warm, problem only occurs during wide turns.
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Old 04-05-2011, 09:10 PM
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During wide turns??????????

Fuel? does anyone else think it could possibly be a fuel pump?
How cold is it outside?

The turns thing is very confusing
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18, 18t, a4, audi, b5, cold, coolant, location, power, problem, revs, rpm, sensor, shifts, start


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